Position Accuracy ?

[+KA7CJH]

It seems like every time I turn on one of my GPS'rs the EPA seems to be increasing. Has anyone else noticed this in their area?

 

I'm in Reno,Nevada and this problem has been happening on all three of my GPS's. I have 2 Garmin Etrex Legends, and one Magellan Explorist 200.. The Garmins are showing up to 45 feet accuracy and the Magellan shows 20 feet. Only a few weeks ago the were down to 5-10 feet off. Any clue as to what is going on?

 

Any feedback is welcomed..

[+cachew nut]

Any feedback is welcomed..

Use the Magellan.

[+budd-rdc]

For me, this behavior is dependent on how the satellites are arranged at a given time. While I was caching yesterday, many of them were clustered to the south, so my EPE was never lower than 18' on my eTrex. Usually, I get 13'-15' on a good day, and 12' in ideal conditions (4 meters). Try again today. Your EPE might be back to your normal range.

 

As for comparing EPEs between Garmin and Magellan (and in my case, Lowrance also), that's apples, oranges, and strawberries.

[+Team Perks]

It's been as reliable for me as it's ever been. I had 9 feet accuracy yesterday.

 

Perhaps you forgot to pay your satellite bill?

[+John Wayne Pooch]

 

Perhaps you forgot to pay your satellite bill?

that's funny.

[+Trucker Lee]

Perhaps you forgot to pay your satellite bill?

 

HEY!!!! Don't you dare give those idiot politicians any more ideas!!!

[+Glenn]

Perhaps you forgot to pay your satellite bill?

 

HEY!!!! Don't you dare give those idiot politicians any more ideas!!!

 

That reminds me of the modem tax hoax. A version for GPS users might look like this...

 

Please forward this to everyone you can...

There is a new bill in the US Congress that will affect ALL GPSr USERS. CNN stated that the Government would in two weeks time decide whether to allow or not allow a Charge to YOU for access to the NAVSTAR satellite nework.

This affects us all! We cannot allow this to happen! Please visit the following URL and fill out the necessary form to let your Congressman know how you feel! The address is http://www.?????.???/????????/. Write your representative!

[+wsgaskins]

For me, this behavior is dependent on how the satellites are arranged at a given time. While I was caching yesterday, many of them were clustered to the south, so my EPE was never lower than 18' on my eTrex. Usually, I get 13'-15' on a good day, and 12' in ideal conditions (4 meters). Try again today. Your EPE might be back to your normal range.

 

As for comparing EPEs between Garmin and Magellan (and in my case, Lowrance also), that's apples, oranges, and strawberries.

 

The main source of 'EPE' is satellite geometry at the particular time and conditions (sky visibility).

 

See here: Sources of GPS Error

 

You can get a better EPE also if you have WAAS turned on, since that gives another satellite (one with a known, fixed position) to measure against. Having WAAS is kind of like having a differential GPS, but one with several meter position accuracy.

[+Rich the Bushwhacker]

Here's a great page describing realtime and predicted GPS performance data. The post assessment for the Reno area for September 1'st shows pretty good coverage for the day. You can pull up post assessment and predition maps here: GPS Operations Center Performance Reports

 

 

However, an unnamed govement entity in the area of Tonopah has been performing some intermittent testing for the past few weeks that affects GPS operation within 296 NM. The advisory is listed here: Coast Guard Navigation Center